Constant-potential alternating generator



(No Model.)

. O. P. STEINMETZ. GONSTANT POTENTIAL ALIERNATING GENERATOR.

Pltented Sept. 29, 1896.

FIELD WITNESE E5- UNITED STATES PATENT OFFICE.

CHARLES P. STEINMETZ, OF SCHENECTADY, NEW YORK, ASSIGNOR TO THE GENERALELECTRIC COMPANY, OF NEW YORK.

C ONSTANT-POTENTlAL ALTERNATING GENERATOR.

SPECIFICATION forming part of Letters Patent No. 568,464, datedSeptember 29, 1896. Application filed April 30, 1894. fierial No.509,455- N m del-l To all whom it may concern: its field-magnets beingenergized by a coil f Be it known that 1, CHARLES P. STEIN- in shunt tothe mains 3 4, through the leads METZ, a subject of the Emperor ofGermany, 5 6, and having a regulating-resistance D in residing atSchenectady, county of Scheneccircuit therewith. From the commutator C 5tady, and State of New York, have invented a series circuit to the mainmachine passes certain new and useful Improvements in by the leads 2 2through the differential se- Dynamo-Electric Machines, of which thefolries winding f upon the field-magnet of the lowing is aspecification. machine F, the armature of which is in series Myinvention relates to dynamo-electric in the lead 4 between the maineXciterE and :0 machines, and more particularly to the large thefield-magnet of the main generator A.

generators used for alternating-current work, D is a resistance in shuntbetween the leads either for long-distance transmission or for 2 2",serving to prevent sparking at the comcentral-station plants, and hasfor its object mutator. I to provide a convenient means of compound- Theoperation of my improved method and 15 ing such generators, capable ofeasy regulameans of compounding is as follows: During tion, andaccurately providing for all loads the normal working of the machine thecoun to which the generating capacity of the mater electromotive forceof the machine F is chines is adapted. so proportioned to the directelectromotive To the ends pointed out I provide, as is force of theexciter E by means of the regu- 7o 20 usual with such machines, aseparate exciter lating-resistance D that the field-magnet for itsfield-magnets, and I also provide a winding A is sufliciently energizedto maincommutator in one of the series leads of the tain the potentialof the current delivered by machine by which the current is rectifiedthe armature A lVhen, however, the load while passing around thefield-magnet of a increases, and with the load the current, and thirdmachine, presently to be referred to. the drop of potential incidentthereto takes The third machine to which reference is made place, thesame increase of current increases has also a winding upon itsfield-magnet in the effect of the differential series winding shuntacross the mains from the exciter to f, diminishing the counterelectromotive the field-magnets of the large generator. force of thethird machine F, thus allowing 3oThethirdmachineisacounter-electromotivean increased excitation of thefield-magnet force generator in series with the exciter. A andincreasing the potential of the deliv- The arrangement indicated allowsme to opered current, While on a decrease of load in pose the twoelectromotive forces to one anthe main circuit the reverse of thisoperation other and get a very close and accurate comtakes place. I mayalso change this differ- 5 pounding effect by varying their ratio, sothat entiation of the two forces so far as to make the electromotiveforce of the exciter is conthem assisting instead of opposingelectrotrolled by the resultant effect of the two. opmotive forces, aswhere the capacity of the posing electromotive forces. machine would beso taxed that the differen- The accompanying drawing shows in diatialwinding f upon the field-magnet of the 0 40 gram the arrangement justdescribed. motor or counter-electromotive-force ma- A indicatesdiagrammatically the main chine would become so highly energized as togenerator, of which A is the field-magnet reverse the polarity of themachine and thus winding, A the armature-winding, B B the cause it togenerate additional electromotive collector-rings, and C the commutatorin the force, acting to assist that of the exciter and 5 45 lead to thecollector-ring 13. still more highly energize the field-magnets 1 and 2are the mains leading to the work. of the main alternator. Such anarrange- E is the exciting-machine, shunt Wound, as ment, however I donot contemplate cmis customary, its armature being connected ployinginpractice, unless fora few moments, by the leads 3 4 to the field-magnetcoil A of when a sudden load is thrown upon the ma- 50 the main machine.chine which it is not adapted to carry con- F is the third machinealready alluded to, secutively. Under such circumstances the regulationis not so effective and the machine varies somewhat in electroinotiveforce and output.

Although I have described my improved method in its relation to analternating-current machine, in which it is of greatest efficaey ascompared with other systems, I do not intend to limit myself to its usein that relation only, but I intend to embrace in the scope of theclaims continuous-cnrrent machinery, as this requires no modification inthe principle of invention and no practical modification in theapparatus embodying the principle, the substitution of a commutator fora collecting-ring being an immaterial change in the practice of myinvention.

I find a material advantage in the use of the special apparatus hereinset out, inasmuch as the saturation-curve of thecountereleetromotive-force machine modifies that of the field-magnetsof: the main generator, so that the current rises in potential slowly atfirst, and as thelimit of load is reached, faster and faster, thusmaintaining the proper electromotive force of the machine under itsextreme capacity, whereas with ordinary means of exciting thecharacteristic rises most rapidly at about half-load and after thatfalls slightly.

\Vhat I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. The combination of a dynamo-electric generator, having its fieldexcited by the resultant action of a main-exciter source, and aregulatirig-dynamo machine in series therewith, and a field-coil on theregulating-machine whose excitation is varied proportion ally to thecurrent flowing in the circuit of the main machine, as set forth.

2. The combination of an alternator, an exciter therefor and aregulating-dynamo in the exeiter-circuit, whose field is energized bycurrent from the exciter and by the commutated or rectified current ofthe alternator, as set forth.

3. The combination of an alternator, an exeiter, a regulating-machine inthe excitcrcircuit, and a field-coil on the regulating-machine energizedby the eommutatcd or recti fied current of the alternator, as set forth.

l. The combination with an alternatingcurrcnt dynamo-electric machine,of a sepa' rate exciter and a counter-elcctrom otive-i'orce machine,having a differential series coil upon its field-magnets, the exciterand counterelectromotive-force machine being in the circuit with thefield -magnet winding of the main machine; whereby the increase of current incident to additional load on the alternator acts to cut down thecounter electromotive force, and vary the excitation of thefield-magnets.

5. The combination of analternating-current dynamo-electric machine, aseparate exciter furnishing eleetromotive force for the field-magnetsthereof, a counter-eleetromotive-force machine in the same field-magnetcircuit, a dilterential series coil upon the field-magnet of thecounter-electromotiveforce machine, and a commutator in the lead fromthe main machine to the differential series coil; all arranged, asherein described and set out, to vary the effect of thecounterelectromotive -forcc armature inversely to changes in the load.

In witness whereof I have hereunto set in y hand this 28th day of April,189i.

CHARLES P. ETEINMETZ.

\Vitnesses:

T. J. J onNs'roN, 13. i3. IIULL.

